Peltodytes lengi

Crawling Water Beetle

Peltodytes lengi, Crawling Water Beetle photo

Family: Haliplidae

Subfamily: Haliplinae

Tribe: Haliplini

Length: 3.5 - 4.0 mm


The family's common name mentions "creeping," and Dillon and Dillon (1972) say the beetles "crawl leisurely and rather awkwardly along." Nevertheless, the beetle in this photo swam very quickly indeed, seldom stopping during the twenty minutes it was having its picture made.

Adults in this family may overwinter out of the water, or may continue to swim throughout the winter. J.R. Hickman in 1931 observed these beetles swimming up to a hole in the ice to renew their air bubble.

Species of Peltodytes are small, but they tend to be noticed nevertheless because of their bright gold metallic coloration.

Peltodytes lengi investigates Mayfly nymph, image
Peltodytes investigates Mayfly nymph, image

Visible in the upper photo at the rear of the beetle is a bubble of air the beetle takes with it as it swims underwater. Air may be stored under the elytra, and also under the much-enlarged first segments (coxae) of the back legs.

Right: A Peltodytes investigates a Mayfly nymph.

Members of the genus Peltodytes may be found in ponds, ditches, and streams (especially the calm backwater areas of streams). They don't require pristine water, and seem to flourish at the ponds at strip mine and gas well sites.

Note that this is both the family page for Haliplidae and the species page for Peltodytes lengi.